In the field of imprinting design onto articles of manufacturer using dye-sublimation, images are transferred from a carrier medium using heat and pressure to activate the printed dyes, causing them to turn gaseous through sublimation from their solid state and to subsequently diffuse into a softened polymer matrix under the influence of heat and pressure. For example, an early patent disclosing a dye sublimation transfer was presented in U.S. Pat. No. 4,021,591 issued to Devries. Another sublimation example is shown in a method of imaging a ceramic mug as disclosed in U.S. Pat. No. 4,943,684 issued to Kramer.
Certain fibrous materials such as polyester fabric and certain synthetic organic polymers such as acetyl, polycarbonate, and nylon can accept the diffusion of sublimable or disperse dyes directly and have no need to be coated before receiving the image. However, their natural ability to accept the diffusion of the dye does not ensure long term persistence of these dyes and often the image will blur or fade over time.
For this reason, and to render articles suitable for dye sublimation decoration on persistent, long-term hosts, synthetic organic coatings are typically formulated and employed to pre-coat the substrate being decorated prior to the transfer of the image. An example patent disclosing such coatings used prior to the sublimation of images onto ceramic tiles is U.S. Pat. No. 4,174,250 issued to Durand.
In the field of cell phone cases, aluminum panels have been designed for incorporation into cell phone and tablet cases and which are prepared for the reception of a transferred image by the process of dye-sublimation. These cases both protect the phone against dropping and causing damage to the screen and phone housing, and also allow a panel to be attached or fitted into the case with a customized image applied onto it. In some applications, the consumer can design and customize the phone with selected photos or graphical images of their choice. Dye sublimation is the preferred method of imaging these panels as it provides a sub-surface decoration that protects the image against scratches, abrasion, and chemical attack. Alternative direct printing processes such as ultraviolet printing that utilize a post-print coating or laminate applied after the imaging process do not provide a comparable level of durability, and is therefore not a candidate for cell phone or tablet case use.
Hence, heretofore the selection of aluminum as the preferred substrate for the coated panel has been due to the combination of the ease of coating application, the ease of cutting the metal with CNC (computer numerically controlled) or die-cutting equipment, the rigidity of the media, and the ability for it to withstand the imaging process temperatures which are typically between 350-400 degrees Fahrenheit (F.) for 1-2 minutes. However, the use of aluminum as a substrate has limitations. Aluminum panels require curved forming or bending to insert them into a phone case, and often the metal bends to a point that exceeds its resiliency and will not return to its original flat shape. Further, such aluminum inserts are generally only 0.040-0.050 inches thick and are therefore easily deformable.
In addition, aluminum inserts are prone to scratching and are easily marred with use thereby detracting from the infused image. A metal insert must be coated with first a white coating and then a clear coating as dye sublimation images require a substantially clear dye receptive coating to receive the image, and a substantially white and light-reflective layer underneath the clear layer. In the case of aluminum the natural color and appearance of the metal requires the white layer to be applied first, with the clear layer to be deposited thereon. Any wear to these layers distorts the images placed thereon by interfering with the desirable scattering of reflected light within the coating.
Another shortcoming of the use of aluminum as the substrate for these phone case inserts is weight. When being shipped in bulk to customers boxes of inserts weigh more than they would if they were made of other lighter substrates, such as plastic. This additional weight also adds cost to the manufacturing of the inserts.
Finally, the greatest shortcoming of the use of a metal substrate, including aluminum, for phone and consumer electronic casing inserts is that metal conducts electricity and interferes with phone signals. In the case of the newer smart phones capable of scanning bar-codes and being employed to pay for items at retail point-of-sale registers, the metallic phone insert completely prevents the phone from operating in the manner intended.
Therefore, what is needed is a manufacturing process to economically produce a non-metal, plastic insert that may be included into a phone case and also facilitate the dye sublimation transfer printing onto that substrate.